gpu: Reuse transfer buffers more aggresively

gpu/command_buffer/service/command_buffer_service.h

Index: gpu/command_buffer/service/command_buffer_service.h
diff --git a/gpu/command_buffer/service/command_buffer_service.h b/gpu/command_buffer/service/command_buffer_service.h
index b1f8fa15fea6a2d3da4a9681f8dad587a01d6c35..5a3591f5421c8e39377dbdbb6f08bb94d8e6cd3f 100644
--- a/gpu/command_buffer/service/command_buffer_service.h
+++ b/gpu/command_buffer/service/command_buffer_service.h
@@ -7,6 +7,7 @@
 
 #include "base/callback.h"
 #include "base/memory/shared_memory.h"
+#include "base/synchronization/lock.h"
 #include "gpu/command_buffer/common/command_buffer.h"
 #include "gpu/command_buffer/common/command_buffer_shared.h"
 
@@ -36,6 +37,7 @@ class GPU_EXPORT CommandBufferService : public CommandBuffer {
   virtual void DestroyTransferBuffer(int32 id) OVERRIDE;
   virtual Buffer GetTransferBuffer(int32 id) OVERRIDE;
   virtual void SetToken(int32 token) OVERRIDE;
+  virtual void SetAsyncToken(uint32 token) OVERRIDE;
   virtual void SetParseError(error::Error error) OVERRIDE;
   virtual void SetContextLostReason(error::ContextLostReason) OVERRIDE;
 
@@ -67,6 +69,8 @@ class GPU_EXPORT CommandBufferService : public CommandBuffer {
                               size_t size);
 
  private:
+  State GetStateImpl();

[reveman, 2014/01/22 17:30:04]

Can you adjust the name of this so it's clear |lock_| must be acquired before
calling this function? Maybe GetStateImplWithLockAcquired().

+
   int32 ring_buffer_id_;
   Buffer ring_buffer_;
   scoped_ptr<base::SharedMemory> shared_state_shm_;
@@ -79,9 +83,11 @@ class GPU_EXPORT CommandBufferService : public CommandBuffer {
   base::Closure parse_error_callback_;
   TransferBufferManagerInterface* transfer_buffer_manager_;
   int32 token_;
+  uint32 async_token_;
   uint32 generation_;
   error::Error error_;
   error::ContextLostReason context_lost_reason_;
+  base::Lock lock_;

[reveman, 2014/01/22 17:30:04]

Would be nice with a comment here describing what this lock is protecting.

[epenner, 2014/01/23 02:52:44]

I'm agreeing with Piman that a lock_ doesn't seem very nice here. It's primarily
just an ownership and/or lifetime thing right? Could clear ownership/lifetime of
the async-token relative to the transfer thread solve this? That might not be
trivial but I think it can be done without locks.

 
   DISALLOW_COPY_AND_ASSIGN(CommandBufferService);
 };